Participants didn't fly anywhere exotic or even leave their time zone. Instead, they spent time at the sleep lab where Eastman works.

Bedtimes Crept Earlier

For the first few nights at the lab, participants slept normally. Then, they were sent to bed one hour earlier every night for three nights.

Meanwhile, their sleep and activity were monitored. They weren't allowed to get out of bed if they didn't fall asleep on time, or to nap during the day.

Their daytime routine was also a bit different than normal.

Letting in the Light

First thing in the morning, participants didn't roll out of bed, grab a bowl of cereal, and brush their teeth.

You would need two hours at the start of your day to match the researchers' plan.

The participants sat at a desk in front of a light box, which pumped out bright light for 30 minutes at a time. Then the light box switched off for half an hour, for four cycles per morning of bright light.

In the afternoon, each participant took two pills. They didn't know it, but one of the pills was a sham (placebo).

What about the second pill? For some, it contained half a milligram of melatonin. Others got a higher dose of melatonin (3 milligrams). A third group just got another placebo pill. No one knew which pill was which.

The timing of the pills was adjusted slightly each day to allow for the "time change."

Continued

About Melatonin

Melatonin is a hormone produced by the pineal gland, which is found in the brain. It plays a role in the sleep-wake cycle of your body's internal clock.

Normally, melatonin levels rise in the mid-to-late evening, stay high for most of the night, and fall in the early morning.

Melatonin supplements are widely available. Researchers don't agree on whether or how much those supplements help with sleep problems, including jet lag.

What Worked

Every day, participants took surveys about how they felt and rated their sleepiness throughout the study. They also kept sleep diaries and wore activity monitors.

The body clocks of those who took melatonin adapted better to the new schedule. The higher dose of melatonin fared best in that regard, but not by much. Plus, people who took the higher dose were sleepier in the evenings after taking the pill.

"Therefore, we recommend using the 0.5 mg dose in combination with morning intermittent bright light and an advancing sleep schedule in any situation in which people need to advance their circadian rhythms," write the researchers.

That includes people preparing to fly east and those with delayed sleep-phase syndrome, the researchers add.

People with delayed sleep-phase syndrome fall asleep very late and have trouble getting up in time for work, school, or other reasons.

What about people flying west? The study doesn't address that. Flying west sets the clock backward -- the opposite of what Eastman's team studied.